DSSSB 6 September 2024
Medical & Surgical Nursing
Easy
A patient with hypokalemia is most likely to show which change on an ECG?
Appeared in: DSSSB 6 September 2024
Explanation
- Hypokalemia (low serum potassium) alters the electrical stability of myocardial cells, specifically by delaying ventricular repolarization.
- This delay manifests on the ECG with several characteristic findings: ST-segment depression, flattening of the T wave, and the appearance of a prominent U wave.
- The U wave, thought to represent repolarization of the Purkinje fibers, is normally small or absent but becomes more apparent as repolarization is prolonged by low potassium levels.
Why Other Options Were Wrong
- Option A: Tall, tented T waves are the classic, early sign of hyperkalemia (elevated potassium), which is the opposite of hypokalemia.
- Option C: A widened QRS complex indicates slowed conduction through the ventricles, a dangerous sign of moderate to severe hyperkalemia.
- Option D: The QT interval is primarily influenced by calcium levels. A shortened QT interval is characteristic of hypercalcemia (high calcium).
Related Visual
Clinical Relevance
- Nursing practice connection: Use the key finding related to ECG interpretation for electrolyte imbalances, specifically hypokalemia to guide bedside assessment, documentation, and the next nursing action.
- Nurses must be able to recognize ECG changes related to potassium imbalances, as both hypokalemia and hyperkalemia can lead to life-threatening cardiac arrhythmias.
- For a patient receiving potassium-wasting diuretics (e.g., furosemide), the appearance of a prominent U wave is a critical finding that should prompt the nurse to notify the provider and check electrolyte levels.
- Hypokalemia increases the risk of digoxin toxicity, so nurses must be especially vigilant in monitoring patients on both medications.
How to Approach the Question
- Identify the core concept from the stem: The question asks for the specific ECG finding associated with 'hypokalemia' (low potassium).
- Recognize this as a direct recall question that tests your knowledge of how electrolyte imbalances affect the heart's electrical activity.
- Systematically evaluate each option:
- Option A (Tall, tented T waves): Recall that this is the hallmark of the opposite condition, hyperkalemia. Eliminate it.
- Option B (Prominent U wave): Recall that this, along with a flat T wave and ST depression, is a classic sign of hypokalemia. This is a strong candidate.
- Option C (Widened QRS complex): Recall that this is a sign of severe hyperkalemia, indicating slowed ventricular conduction. Eliminate it.
Concept Tested & Keywords
- Concept Tested: ECG interpretation for electrolyte imbalances, specifically hypokalemia.
- Stem keywords: hypokalemia, ECG
- Lead-in keywords: most likely
Question ID
QZI7pGkHTiLDxzlZ3ZkzZ4
Reference Book
E6 Medicine Harrison 22e Part 1 pp. 1915-1917, 1911-1913
Practise the full DSSSB 6 September 2024
Attempt every question from this paper in a timed mock, then review the full solution for each one.
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